Digital printing systems offer many advantages such as providing short run printing capability with variable content in a cost effective manner. Digital printing systems have been developed using a variety of different technologies including inkjet printing systems and electrophotographic printing systems.
Inkjet printing is a non-contact application of an ink to a receiver medium. Typically, one of two types of inkjet mechanisms are used and are categorized by technology as either “drop on demand” inkjet or “continuous inkjet.” The first inkjet technology, drop-on-demand inkjet printing, provides ink drops that impact upon a recording surface using a pressurization actuator, for example, a thermal, piezoelectric, or electrostatic actuator. One commonly practiced drop-on-demand technology uses thermal actuation to eject ink drops from a nozzle. A heater, located at or near the nozzle, heats the ink sufficiently to boil, forming a vapor bubble that creates enough internal pressure to eject an ink drop. This form of inkjet is commonly termed “thermal inkjet.”
The second inkjet technology, commonly referred to as continuous inkjet printing, uses a pressurized ink source to produce a continuous liquid jet stream of ink by forcing ink, under pressure, through a nozzle. The stream of ink is perturbed using a drop forming mechanism such that the liquid jet breaks up into drops of ink in a predictable manner. One continuous printing technology uses thermal stimulation of the liquid jet with a heater to form drops that eventually become print drops and non-print drops. Printing occurs by selectively deflecting drops so that print drops reach the receiver medium and non-print drops are caught by a collection mechanism. Various approaches for selectively deflecting drops have been developed including electrostatic deflection, air deflection, and thermal deflection.
Electrophotographic printing systems form an electrostatic latent image on a photoreceptor by uniformly charging the photoreceptor and then discharging selected areas of the uniform charge to yield an electrostatic charge pattern corresponding to the desired image (i.e., a “latent image”). After the latent image is formed, charged toner particles are brought into the vicinity of the photoreceptor and are attracted to the latent image to develop the latent image into a toner image. After the latent image is developed into a toner image on the photoreceptor, a receiver medium is brought into juxtaposition with the toner image. A suitable electric field is applied to transfer the toner particles of the toner image to the receiver medium to form the desired print image on the receiver medium. The receiver medium is then subjected to heat or pressure to permanently fix (i.e., “fuse”) the print image to the receiver. Plural print images (e.g., separation images of different colors) can be overlaid on the receiver before fusing to form a multi-color print image on the receiver.
Some digital printing systems are adapted to print on continuous webs of receiver media, while others are adapted to print on cut sheets of receiver media. In web printing systems, a continuous web of receiver media is moved from a source roll through and travels along a web transport path past printing system components which deposit marking material to form printed images. In cut sheet printing systems, individual sheets of receiver media are moved along a sheet transport path past printing system components which deposit marking material to form printed images.
Web printing systems and cut sheet printing systems each have different advantages which are useful for various printing applications. However, equipment cost and space allocation make it difficult for companies to support both media formats. There is a need for a printing system that can be used to print on both continuous webs of receiver media as well as cut sheets of receiver media.